ALBERT

Description: In the last few decades and in the near future CO2-induced ocean acidification is potentially a big threat to marine calcite-shelled animals (e.g. brachiopods, bivalves, corals and gastropods). Despite the great number of studies focusing on the effects of acidification on shell growth, metabolism, shell dissolution and shell repair, the consequences for biomineral formation remain poorly understood. Only a few studies have addressed the impact of ocean acidification on shell microstructure and geochemistry. In this study, a detailed microstructure and stable isotope geochemistry investigation was performed on nine adult brachiopod specimens of Magellania venosa (Dixon, 1789). These were grown in the natural environment as well as in controlled culturing experiments under different pH conditions (ranging from 7.35 to 8.15±0.05) over different time intervals (214 to 335 days). Details of shell microstructural features, such as thickness of the primary layer, density and size of endopunctae and morphology of the basic structural unit of the secondary layer were analysed using scanning electron microscopy. Stable isotope compositions (δ13C and δ18O) were tested from the secondary shell layer along shell ontogenetic increments in both dorsal and ventral valves. Based on our comprehensive dataset, we observed that, under low-pH conditions, M. venosa produced a more organic-rich shell with higher density of and larger endopunctae, and smaller secondary layer fibres. Also, increasingly negative δ13C and δ18O values are recorded by the shell produced during culturing and are related to the CO2 source in the culture set-up. Both the microstructural changes and the stable isotope results are similar to observations on brachiopods from the fossil record and strongly support the value of brachiopods as robust archives of proxies for studying ocean acidification events in the geologic past.

Description: Throughout the last few decades and in the near future CO2–induced ocean acidification is potentially a big threat to marine calcite-shelled animals (e.g., brachiopods, bivalves, corals and gastropods). Despite the great number of studies focusing on the effects of acidification on shell growth, metabolism, shell dissolution and shell repair, the consequences on biomineral formation remain poorly understood, and only few studies addressed contemporarily the impact of acidification on shell microstructure and geochemistry. In this study, a detailed microstructure and stable isotope geochemistry investigation was performed on nine adult brachiopod specimens of Magellania venosa (Dixon, 1789), grown in the natural environment as well as in controlled culturing experiments at different pH conditions (ranging 7.35 to 8.15±0.05) over different time intervals (214 to 335 days). Details of shell microstructural features, such as thickness of the primary layer, density and size of endopunctae and morphology of the basic structural unit of the secondary layer were analysed using scanning electron microscopy (SEM). Stable isotope compositions (δ13C and δ18O) were tested from the secondary shell layer along shell ontogenetic increments in both dorsal and ventral valves. Based on our comprehensive dataset, we observed that, under low pH conditions, M. venosa produced a more organic-rich shell with higher density of and larger endopunctae, and smaller secondary layer fibres, when subjected to about one year of culturing. Also, increasingly negative δ13C and δ18O values are recorded by the shell produced during culturing and are related to the CO2–source in the culture setup. Both the microstructural changes and the stable isotope results are similar to observations on brachiopods from the fossil record and strongly support the value of brachiopods as robust archives of proxies for studying ocean acidification events in the geologic past.

Description: Donax species dominate the intertidal zone of coastal upwelling sandy beaches worldwide. The population dynamics of West African D. pulchellus and D. rugosus is still unknown. The population dynamics and ecology of surf clam Donax species, D. pulchellus and D. rugosus (Bivalvia: Donacidae), inhabiting two exposed sandy beaches of Ghana, were studied over 12 months period (August 2006 to July 2007). A total of 7,225 individuals of D. pulchellus, La beach and 2,452 individuals of D. rugosus, Chorko beach, were sampled. Two-way analysis of variance revealed a significant difference in the spatial and temporal distribution of the two species (p 〈 0.05). D. pulchellus attains first maturity at a mean length of 7.16 + 1.89 mm, and a maximum size of 11 mm while D. rugosus attains first maturity at a mean length of 20.94 + 6.98 mm, and a maximum size of 33.5 mm. Environmental factors namely, salinity, nitrate, and grain size modulate the growth in shell length of the two species. This book, provide new insight of Donax species as sedentary bivalves of sandy beach ecosystems. The book is useful for marine biologist, benthic ecologist, environmentalist, and chemical ecologist.

Description: Background: DNA barcoding has demonstrated that many discrete phenotypes are in fact genetically distinct (pseudo)cryptic species. Genetically identical, isogenic individuals, however, can also express similarly different phenotypes in response to a trigger condition, e.g. in the environment. This alternative explanation to cryptic speciation often remains untested because it requires considerable effort to reject the hypothesis that the observed underlying genetic homogeneity of the different phenotypes may be trivially caused by too slowly evolving molecular markers. The widespread squat lobster Munida gregaria comprises two discrete ecotypes, gregaria s. str. and subrugosa, which were long regarded as different species due to marked differences in morphological, ecological and behavioral traits. We studied the morphometry and genetics of M. gregaria s. l. and tested (1) whether the phenotypic differences remain stable after continental-scale sampling and inclusion of different life stages, (2) and whether each phenotype is underpinned by a specific genotype. Results: A total number of 219 gregaria s. str. and subrugosa individuals from 25 stations encompassing almost entire range in South America were included in morphological and genetic analyses using nine unlinked hypervariable microsatellites and new COI sequences. Results from the PCA and using discriminant functions demonstrated that the morphology of the two forms remains discrete. The mitochondrial data showed a shallow, star-like haplotype network and complete overlap of genetic distances within and among ecotypes. Coalescent-based species delimitation methods, PTP and GMYC, coherently suggested that haplotypes of both ecotypes forms a single species. Although all microsatellite markers possess sufficient genetic variation, AMOVA, PCoA and Bayesian clustering approaches revealed no genetic clusters corresponding to ecotypes or geographic units across the entire South-American distribution. No evidence of isolation-by-distance could be detected for this species in South America. Conclusions: Despite their pronounced bimodal morphologies and different lifestyles, the gregaria s. str. and subrugosa ecotypes form a single, dimorphic species M. gregaria s. l.. Based on adequate geographic coverage and multiple independent polymorphic loci, there is no indication that each phenotype may have a unique genetic basis, leaving phenotypic plasticity or localized genomic islands of speciation as possible explanations.

Description: Two scleractinian cold-water corals, Desmophyllum dianthus and Caryophyllia huinayensis are abundant on hard substrate, below 18 m depth, throughout the entire fjord Comau in Northern Patagonia, Chile. At “X-Huinay” (42º 23.276’ S, 72º 27.657’ W) on the western side of the central fjord, a recent mass mortality of D. dianthus occurred, while C. huinayensis survived. H2S seeps here support the formation of filamentous chemosynthetic bacterial mats. At this site, sulfide concentrations of up to 100 higher than normal ambient water values have been measured.

Description: Scleractinian corals (or stony corals) are important habitat forming organisms. Their characteristic growth creates three dimensional structures that provide shelter, settlement substrate and habitat to a diversity of organisms. This also holds true for cold water corals (CWC), but current knowledge is limited with only two decades of research. Caryophyllia huinayensis (Carins et al. 2005) is a small solitary scleractinian coral, which can serve as a model organism for the study of metabolism of CWC. This stony coral is commonly found in association with the larger scleractinian coral Desmophyllum dianthus in the Chilean Fjord Region, even in diving depths. As to quantify the basic physiological parameter ‘respiration’, specimens of the whole size range were collected at two stations and acclimatised to in vitro condition. Oxygen microoptodes (based on the dynamic fluorescence quenching principle), a four channel optode array, an intermittent flow system, and online data registration were used to measure the metabolic activity of Caryophyllia huinayensis during in vitro respiration experiments. This species showed oxygen consumption rates, ranging from 0.01mg/l up to 1.61mg/l. The overall metabolic rates are compared with those of other scleractinian corals.

Description: The energy budget is one key to the understanding of an ecosystem and may be determined by its carbon fluxes. The aim of the study was and still is to quantify the carbon flux between newly established arctic hard bottom communities and their pelagial in-situ. A complex setup was constructed to establish a functional in-situ method for hard bottom communities. We used artificial panels, installed in arctic Kongsfjorden at 20 m depth. The panels were colonized by hard bottom organisms over the last decade. These panels were transferred in-situ into benthic chambers. The latter were connected via Tygon-tubes to a multiprobe array (CTD, Seabird 19 V2 plus) allowing measurement of O2-concentrations. A newly designed 16-way valve was used to measure several panels over a period of 72 h in a day and night rhythm.

Description: The cold-water hydrocoral Errina antarctica provides habitat for numerous macroepibenthic species. Gaining knowledge about the highly diverse communities associated with E. antarctica is crucial for efficient protection of the ecosystems, which are strongly threatened by aquaculture and other human activities. This investigation for the first time provides information on quantitative composition of benthic communities associated with E. antarctica. Structure of macroepibenthic community associated with E. antarctica in three bathymetric zones (Zone 1: 10-20 m; Zone 2: 20-30 m; Zone 3: 30-40 m) from four diving sites in the Chilean fjord region is described by analyzing 260 images extracted from videos recorded via ROV. Community compositions were investigated based on abundances using multivariate statistical methods (SIMPER, ANOSIM, MDS). Ecological indices (S, H´, d, J´) were calculated. Distribution of differently sized E. antarctica-colonies (small [diameter 〈 10 cm], medium [10 cm 〈 diameter 〈 20 cm], large [20 cm 〈 diameter]) was investigated and set into context with analysis of community structure. No significant influence of depth on the investigated community was detected. Differences between the four diving sites seem to overlay bathymetric effects. Annelids (mainly genus spirorbis) dominate all bathymetric zones, in line with former investigations. ANOSIM indicated poor distinctness between bathymetric zones (GR=0.062). The MDS-plot showed no grouping of bathymetric zones. Low values of ecological indices in Zone 1 are explained by distribution of E. antarctica-colonies. Abundances of colonies of all sizes decreases with depth, portion of small colonies is highest in Zone 1.